It looks very nice and relaxing right now, but I do think you can add accents in another color if you'd like. You have a lot of options with your current scheme so I'm attaching a few inspiration pics that might help you decide what direction you want to go.

Bright yellow

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Red or pink

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Orange

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Green

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Place the blue shams leaning against the stacked bed pillows & the lumbar in the center of the two shams. l do like the comforter & the lumbar pillow, but agree you need to add some accents to the room. Can you provide us with full room photos?

The sky is the limit as far as accent colors with the white & blue. Since you have a nice tan color for the walls, try these colors: orange, rust, red, yellow, chartreause, wine, light green. Any of these I suggested. Pick two of the above & use each one in three different places. Make sure the two you pick go together. Choose orange for:

Choose yellow for a live orchid. two different shades of yellow for two different sizes of glass pieces and a pice of art:

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